2005 Blazer AC compressor cycling

ryaninvancouve

Hi all, TIA for any ideas you may have...

My Blazer (4.3L) started cycling the AC compressor for no apparent reason. With climate controls and defrost off at idle I was hearing a click (compressor clutch engaging) and idle would jump 300rpm. It will cycle every 3 seconds on and off. My dealer saw it and says it isn't a problem, the compressor will just decide to come on for unknown reasons. He says as long as no dash lights come on it isn't a problem. I think they're idiots who have no idea how to troubleshoot the system. My warranty is up next month so any ideas on what might be causing this would be greatly appreciated!

cheers,

Ryan

jlflemmons

You are correct, they are idiots. Obviously, the compressor clutch is getting a command to engage from somewhere, and if the controls are all off, there is a short somewhere. One trick would be to pull the ac controls and disconnect them. If the compressor continues to cycle, there be a short somewhere. While the idle is computer controlled, and does pick up when the compressor kicks in, I can't speak to where the compressor clutch signal comes from. Could be direct from the a/c controls, or the controls could be telling the computer and the body computer is turning on the clutch.